In general, use periods in academic degrees:
Ph.D.
M.D.
B.A.
The exception is MBA. Most reference books leave the periods out of that one, so we will, too.
In professional certifications, on the other hand, don’t use periods:
CDE
CKD
RD
Sometimes this will result in mixed formats in a single byline:
Jane Johnson, Ph.D., CDE
Abbreviations
Capitalization
Company Names
Dates and Times
Degrees and Certifications
Periods
Plurals
Spaces
